The purpose is often simply to quickly identify the source of the call, if possible, to determine if it's spam and worth blocking directly through the device.
Why do you think posting your request on a website to identify unknown phone numbers will have any results? Do you think your caller watches this site and will know who you are when they see your post and will stop calling you? Just invest in a call blocker.
The purpose is often simply to quickly identify the source of the call, if possible, to determine if it's spam and worth blocking directly through the device.